1. Technical Field
The presently disclosed subject matter relates to a vehicle lamp, and more particularly to a vehicle lamp which has LED light sources.
2. Description of the Related Art
Conventionally, there have been vehicle lamps that have a large number of LEDs arranged as their light sources. Some of the vehicle lamps have been configured to have the following structure, for example. In this structure, the LEDs are mounted on a substrate with the lead frames of the LEDs electrically connected with electrode pads which are formed on the substrate. Furthermore, part of an extension (exterior component) forms reflecting surfaces around the vicinities of the light emitting areas of the LEDs so as to increase the illumination area of light by means of the reflecting surfaces.
In this case, the lead frames are utilized to situate the light emitting areas of the LEDs away from the substrate, thereby increasing the utilization efficiency of light emitted from the light emitting areas of the LEDs for increased illumination intensity. The light emitting areas of the LEDs are also located at shallower positions from the open top ends of the reflecting surfaces (the front of the extension) so that the light can be projected for a wider range of distribution.
If this configuration fails to provide a sufficient coverage of light illumination, then an outer lens having upper lens cut portions may also be arranged over the LEDs. This, however, gives rise to factors responsible for higher cost, including increased parts count, increased machining man-hours, and increased mold cost.
In view of the above, there has been proposed a lamp that is configured as shown in FIG. 1. More specifically, a base 50 formed in a step-like configuration has stages 59, each of which is provided with a protruding holder 51 for an LED to be inserted and attached to. The holders 51 each have a pair of cord insertion grooves. Then, electric cords 52 laid across holders 51 are held in the respective cord insertion grooves.
Each LED 55 has a pair of lead terminals 54 which have a slit 53 and are bent into a U shape. The lead terminals 54 are inserted into lead slots 56 of the holder 51 so that the electric cords 52 are fitted into the respective slits 53 of the lead terminals 54 with their insulation coating cut in. As a result, the slits 53 of the lead terminals 54 and the cores of the electric cords 52 make direct contact with each other, thereby establishing electric connection between the lead terminals 54 of the LED 55 and the electric cords 52.
A reflector 58 having a plurality of reflector portions 57 and an extension portion is also arranged over the LEDs 55. The reflector portions 57 are shaped to form a paraboloid of revolution, and are opposed to the respective LEDs 55. An outer lens is arranged in front of the reflector 58 (for example, see Japanese Patent Application Laid-Open No. 2002-245812).
In the conventional vehicle lamp having the foregoing configuration, the LEDs 55 attached to the respective holders 51 of the base 50 are held in position by means of the lead terminals 54 alone. There is thus the possibility of causing a handling inconvenience during manufacturing in which the reflector 58 accidentally collides with the LEDs 55 to bend the lead terminals 54 in the process of assembling the reflector 58, so that the direction of projection of the LEDs 55 may deviate from a predetermined direction.
Since each individual LED 55 can only illuminate a relatively narrow area, a large number of LEDs 55 are mounted to expand the illumination area if the intended lamp requires a wide range of light distribution. This contributes to increased cost.
For another specific example, there has been proposed a lamp, for example, as shown in Japanese Patent Application Laid-Open No. Hei 6-349306. In this lamp, substrates having surface-mount LEDs mounted thereon are attached to respective stages of a step-like housing. Furthermore, a lens provided with lens cut portions in the side facing toward the LEDs is arranged in front of the LEDs.
In this case, the lamp is composed of four components including the LEDs, the substrates, the housing, and the lens. The positional accuracy of the LEDs with respect to the lens cut portions depends on the accumulation of both the accuracy of mounting position of the LEDs with respect to the substrates and the accuracy of mounting position of the substrates with respect to the housing. In other words, the accuracies of assembly have a high impact on the accuracy of light distribution desired. This may result in uneven light distribution in each individual lamp, and light distribution variations between separate individual lamps.